In connection with the efforts which have been expended in order to develop devices for applying active agents, as well as active agents and film layers, to the skin of a host or patient, a recent significant development in this regard is set forth in U.S. Pat. No. 4,915,102. In that patent a device for either transferring a film layer to the skin or mucosa of a patient or host, or for the application of a film layer combined with an active agent carrier, is disclosed. The devices which are shown in this patent permit the application of a film layer, or a film layer in combination with an active agent carrier, to the skin in a most simple and facile manner, particularly as compared to the prior art up to that time.
As is spelled out in the background section of U.S. Pat. No. 4,915,102, aside from efforts to apply film layers per se, there have also been considerable efforts in connection with the application of active agent carriers themselves. This patent thus includes a discussion of the various transdermal administration systems, including Ciba-Geigy's TRANSDER.RTM.-NITRO and TRANSDERM.RTM.-V systems, as well as a significant improvement represented by U.S. Pat. No. 4,573,996, which is seepage-resistant during use, therefore eliminating prior problems with contamination which were previously encountered in such devices.
There have also been a number of systems which have attempted to employ multiple compartments for the administration of drugs and the like. An early such device is shown in U.S. Pat. No. 4,460,370, FIGS. 6 and 7 of which depict transdermal delivery patches having two compartments separated by a dam to prevent mixing of the contents of these compartments. The reservoirs in the devices of the '370 patent are filled with the drug to be delivered through an aperture in the top of the patch separately and are maintained separate from each other by means of the dam therebetween.
Two later patents directed to transdermal drug delivery systems with multiple reservoirs are disClosed in U.S. Pat. Nos. 4,917,676 and 4,911,707. These patents also employ membranes to separate various compartments, and, in fact, use combinations of permeable and impermeable membranes to enclose these separate compartments and separate them from each other. These patents also disclose use of a heat seal as the barrier between the reservoirs which are of sufficient pressure to prevent bursting. The compartments in these patents are said to hold both an activating agent and an agent which is to be activated thereby.
Another such multi-compartmentalized device is shown in U.S. Pat. No. 4,666,441. In this case the barriers between the compartments are formed by membranes, but at column 5, lines 12-15 thereof it is also stated that when they are not burstable they are heat sealed. Within the compartments themselves, the 441 patent discloses a potential use of different concentrations of the same drug or different vehicles having different drug release rates. The patent also discloses the potential use of different drugs in different compartments. However, the structure of the device shown in the '441 patent employs a single membrane to define more than one reservoir; that is, by heat sealing the area encompassed by the membrane to subdivide the membrane into separate reservoirs. The object is to obtain intermixing between the reservoirs during application, and not to keep the two systems separate even after application to the patient simultaneously. Thus, even where the '441 patent discusses simultaneous application of different drugs, that is only in the context of the use of non-burstable boundaries between the compartments to maintain them separate during application.